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Abstract:

A catalyst system for a marine engine incorporates a catalyst device
within a housing structure. The catalyst device has a rim portion that is
disposed within first and second flange surfaces of first and second
housing structures. A gasket is provided which is configured to have an
opening that allows the rim portion of the catalyst device to be
constrained between the first and second flange portions but not between
the gasket and either of the first and second flange surfaces.

Claims:

1-2. (canceled)

3. An exhaust system for a marine engine, comprising:a first catalyst
device comprising a first catalyst material disposed within a first
catalyst structure, said first catalyst structure having a first
generally tubular portion, said first generally tubular portion having a
first central axis;a first rim portion extending from an end of said
first generally tubular portion, said first rim portion being disposed in
a first plane which is generally perpendicular to said first central
axis;a first housing structure configured to direct an exhaust gas away
from said marine engine, said first housing structure having a first
flange surface;a second housing structure configured to direct said
exhaust gas away from said first housing structure, said second housing
structure having a second flange surface;a gasket, said first and second
housing structures being configured to be attached together with said
gasket being disposed between said first and second flange surfaces, said
gasket having a first opening formed through its thickness, said first
opening being configured to receive said first rim portion
therein;wherein said gasket is engaged by said first and second flange
surfaces on axially distally opposite sides of said gasket without said
first rim portion therebetween;said first rim portion is disposed within
said first opening and in direct contact with said first and second
flange surfaces when said first and second flange surfaces are attached
together;said first rim portion is engaged by said first and second
flange surfaces at a first engagement location spaced radially outwardly
of said first central axis by a first radial distance;said gasket is
engaged by said first and second flange surfaces at a second engagement
location spaced radially outwardly of said first central axis by a second
radial distance; andsaid second radial distance is greater than said
first radial distance.

4. The exhaust system of claim 3, further comprising:a second catalyst
device comprising a second catalyst material disposed within a
second-catalyst structure, said second catalyst structure having a second
generally tubular portion, said second generally tubular portion having a
second central axis; anda second rim portion extending from an end of
said second generally tubular portion, said second rim portion being
disposed in a second plane which is generally perpendicular to said
second central axis.

5. The exhaust system of claim 4, wherein:said gasket has a second opening
formed through its thickness, said second opening being configured to
receive said second rim portion therein.

6. The exhaust system of claim 5, wherein:said second rim portion is
disposed within said second opening and in direct contact with said first
and second flange surfaces when said first and second flange surfaces are
attached together.

7. The exhaust system of claim 6, further comprising:a third catalyst
device comprising a third catalyst material disposed within a
third-catalyst structure, said third catalyst structure having a third
generally tubular portion, said third generally tubular portion having a
third central axis; anda third rim portion extending from an end of said
third generally tubular portion, said third rim portion being disposed in
a third plane which is generally perpendicular to said third central
axis.

8. The exhaust system of claim 7, wherein:said gasket has a third opening
formed through its thickness, said third opening being configured to
receive said third rim portion therein.

9. The exhaust system of claim 8, wherein:said third rim portion is
disposed within said third opening and in direct contact with said first
and second flange surfaces when said first and second flange surfaces are
attached together.

10. The exhaust system of claim 9, wherein:said first, second and third
planes are coplanar with each other and said first, second and third
central axes are parallel with each other.

11-12. (canceled)

13. An exhaust system for a marine engine, comprising:a plurality of
catalysts, each of said plurality of catalysts comprising a catalyst
material disposed within a catalyst structure, each of said catalyst
structures having a generally tubular portion, each of said generally
tubular portions having a central axis, each of said plurality of
catalysts further comprising a rim portion extending from an end of said
generally tubular portion, said rim portion being disposed in a rim plane
which is generally perpendicular to said central axis;a first housing
structure configured to direct an exhaust gas away from said marine
engine, said first housing structure having a first flange surface;a
second housing structure configured to direct said exhaust gas away from
said first housing structure, said second housing structure haying a
second flange surface;a gasket, said first and second housing structures
being configured to be attached together with said gasket being disposed
between said first and second flange surfaces, said gasket having a
plurality of openings formed through its thickness, each of said
plurality of openings being configured to receive one of said rim
portions of said plurality of catalysts therein;wherein said gasket is
engaged by said first and second flange surfaces on axially distally
opposite sides of said gasket without said rim portions therebetween;each
of said rim portions of said plurality of catalysts is disposed within a
preselected one of said plurality of openings;each of said rim portions
is engaged by said first and second flange surfaces at a respective first
engagement location spaced radially outwardly of a respective central
axis by a first radial distance;said gasket is engaged by said first and
second flange surfaces at a respective second engagement location spaced
radially outwardly of the respective central axis by a second radial
distance; andsaid second radial distance is greater than said first
radial distance.

14. The exhaust system of claim 13, wherein:each of said central axes of
each of said generally tubular portions being disposed in a common
alignment plane which is generally perpendicular to said rim plane.

15. The exhaust system of claim 14, wherein:said plurality of catalysts is
disposed in serial fluid communication with said first and second housing
structures.

16. An exhaust system for a marine engine, comprising:a plurality of
catalysts, each of said plurality of catalysts comprising a catalyst
material disposed within a catalyst structure, each of said catalyst
structures having a generally tubular portion, each of said generally
tubular portions having a central axis, each of said plurality of
catalysts further comprising a rim portion extending from an end of said
generally tubular portion, said rim portion being disposed in a rim plane
which is generally perpendicular to said central axis;a first housing
structure configured to direct an exhaust gas away from said marine
engine, said first housing structure having a first flange surface;a
second housing structure configured to direct said exhaust gas away from
said first housing structure, said second housing structure having a
second flange surface;a gasket, said first and second housing structures
being configured to be attached together with said gasket being disposed
between said first and second flange surfaces, said gasket having a
plurality of openings formed through its thickness, each of said
plurality of openings being configured to receive one of said rim
portions of said plurality of catalysts therein, each of said rim
portions of said plurality of catalysts being disposed within a
preselected one of said plurality of openings;wherein:said gasket is
engaged by said first and second flange surfaces on axially distally
opposite sides of said gasket without said rim portions therebetween;each
of said rim portions is engaged by said first and second flange surfaces
at a respective first engagement location spaced radially outwardly of
the respective central axis by a first radial distance;said gasket is
engaged by said first and second flange surfaces at a respective second
engagement location spaced radially outwardly of the respective central
axis by a second radial distance; andsaid second radial distance is
greater than said first radial distance.

17. The exhaust system of claim 16, wherein:each of said central axes of
each of said generally tubular portions being disposed in a common
alignment plane which is generally perpendicular to said rim plane.

18. The exhaust system of claim 17, wherein:said plurality of catalysts is
disposed in serial fluid communication with said first and second housing
structures.

19. The exhaust system of claim 3, wherein:said first rim portion extends
to said first radial distance to reach said first engagement location;
andsaid first rim portion does not extend to said second radial distance
and does not reach said second engagement location.

20. The exhaust system of claim 13, wherein:each of said rim portions
extends to the respective said first radial distance to reach the
respective said first engagement location; andeach said rim portion does
not extend to the respective said second radial distance and does not
reach the respective said second engagement location.

21. The exhaust system of claim 16, wherein:each of said rim portions
extends to the respective said first radial distance to reach the
respective said first engagement location; andeach of said rim portions
does not extend to the respective said second radial distance and does
not reach the respective said second engagement location.

Description:

CROSS REFERENCE TO CO-PENDING PATENT APPLICATION

[0001]This patent application is a member of a family of co-pending and
commonly owned patent applications which were all filed on ______, 2005.
This family includes patent application (M09964) which was filed by White
(Ser. No. ______), patent application (M09966) which was filed by White
(Ser. No. ______), patent application (M09967) which was filed by Burk et
al (Ser. No. ______), patent application (M09968) which was filed by
White et al (Ser. No. ______), patent application (M09969) which was
filed by White et al (Ser. No. ______), patent application (M09971) which
was filed by White (Ser. No. ______), patent application (M09972) which
was filed by White et al (Ser. No. ______), patent application (M09974)
which was filed by White (Ser. No. ______), patent application (M09976)
which was filed by White (Ser. No. ______).

FIELD OF THE INVENTION

[0002]The present invention is generally related to a catalyst device for
a marine engine and, more particularly, to a catalyst device that is
generally tubular and has a rim portion attached to one end of the
generally tubular portion.

DESCRIPTION OF THE RELATED ART

[0003]Those skilled in the art of internal combustion engines are aware of
many types of catalyst systems that are available to improve exhaust
emissions emitted by the engines.

[0004]U.S. Pat. No. 4,848,082, which issued to Takahashi et al. on Jul.
18, 1989, describes an exhaust gas purifying device for a marine engine.
A catalyst exhaust system for an outboard motor is described. A throttle
control arrangement is incorporated for assuring rapid heating of the
catalyst to its operating temperature.

[0005]U.S. Pat. No. 4,900,282, which issued to Takahashi et al. on Feb.
13, 1990, describes an exhaust gas purifying device for a marine engine.
A catalytic exhaust system for a marine outboard drive is described
wherein the catalyzer material is supported by a heat conductive bracket
and the bracket is cooled by a cooling jacket that is supplied with
coolant from the engine cooling jacket. In one embodiment, the water
jacket is cooled both internally and externally by delivering water from
the cooling jacket into the exhaust system to impinge upon a wall of the
cooling jacket.

[0006]U.S. Pat. No. 5,133,185, which issued to Gilbreath et al. on Jul.
28, 1992, describes an anti-moisture device for engine exhaust systems.
The device is intended to remove moisture droplets from an interior
surface of a duct, characterized by an outer edge secured to the interior
surface of the duct, an inner edge surrounding an opening, and a
connecting wall between the outer edge and the inner edge. The inner edge
of the anti-moisture device is positioned closer to a downstream end of
the duct than the outer edge whereby the connecting wall is positioned at
an angle relative to the interior surface of the duct. Moisture droplets
traveling upstream will be caught between the connecting wall and the
interior surface of the duct, on the downstream side of the device.

[0007]U.S. Pat. No. 5,167,934, which issued to Wolf et al. on Dec. 1,
1992, describes a catalyzer installation for boat engines and a method
for catalytic exhaust gas cleaning. The invention is intended for use in
boat engines and the catalyzer is subdivided into a reduction part
location upstream in the exhaust gas line and an oxidation part located
coaxially downstream after it. An intermediate space is located between
the reduction and oxidation parts. Both catalyzer parts are surrounded by
a preferably cylindrical, water cooled casing and the casing has a
downstream secondary air inlet to which a secondary air blower can be
connected, the secondary air separating the very hot catalyzer from the
double walled, water cooled casing and, in particular, flowing around the
oxidation catalyzer part in counterflow for air preheating so that the
air preheating in this manner is passed through the intermediate space
into the oxidation part.

[0008]U.S. Pat. No. 5,203,167, which issued to Lassanske et al. on Apr.
20, 1993, describes a marine propulsion device internal combustion engine
and method for making the same. The propulsion device comprises a
driveshaft housing, a propeller shaft rotatably supported by the
driveshaft housing, an internal combustion engine drivingly connected to
the propeller shaft, the engine including a cylinder block defining a
cylinder having an exhaust port, and defining an exhaust outlet, and an
exhaust passage between the exhaust port and the exhaust outlet, an
exhaust catalyst apparatus mounted on the cylinder block, the apparatus
including a tongue extending into the cylinder block exhaust passage and
dividing the cylinder block exhaust passage into an upstream portion
communicating with the exhaust port and a downstream portion
communicating with the exhaust outlet. The apparatus includes an exhaust
passage communicating between the upstream portion and the downstream
portion. The catalyst is located in the apparatus exhaust passage.

[0009]U.S. Pat. No. 5,212,949, which issued to Shiozawa on May 25, 1993,
describes an exhaust gas cleaning system for a marine propulsion unit. It
is intended for use with a watercraft engine. A plurality of horizontally
positioned exhaust ports are located within an engine cylinder head. An
exhaust manifold communicates with each of the exhaust ports at a first
end and forms a gas collecting pipe at its second end. The second end of
the gas collecting pipe is positioned above the exhaust ports. A
generally horizontally positioned exhaust pipe extends from the second
end of the gas collecting pipe and continues in a rearward direction.
Means are provided for introducing coolant from the engine into the
rearwardly extending portion of the exhaust pipe.

[0010]U.S. Pat. No. 5,306,185, which issued to Lassanske et al. on Apr.
26, 1994, describes catalytic elements for marine propulsion devices. A
marine propulsion device comprising a propulsion unit including a
propeller shaft, a housing including an exhaust gas inlet and an exhaust
gas outlet, a catalytic element supported in the housing for
reorientation from a first orientation to a second orientation different
from the first orientation, and structure for reorienting the element
from the first orientation to the second orientation is described.

[0011]U.S. Pat. No. 5,324,217, which issued to Mineo on Jun. 28, 1994,
describes an exhaust system for a small boat. It includes a water trap
device for precluding water entering the exhaust system if the watercraft
becomes inverted from entering the engine through the exhaust system.
Coolant from the engine is delivered to a cooling jacket that encircles
the entire exhaust system and is introduced into the exhaust gases
downstream of the water trap so that in the event of inversion and
righting the engine coolant will also not enter the exhaust system. This
also provides protection for catalyzers in the exhaust system.

[0012]U.S. Pat. No. 5,408,827, which issued to Holtermann et al. on Apr.
25, 1995, describes a marine propulsion device with improved catalyst
support arrangement. An internal combustion engine includes an exhaust
port, an exhaust conduit communicating with the exhaust port and having
an inner surface, the conduit including first and second conduit portions
having respective ends, the first and second conduit portions being
connected end to end, a catalyst which is located within the conduit and
which includes catalytic material and a sleeve surrounding the catalytic
material, wherein the sleeve has a length and an outer surface spaced
from the inner surface of the conduit along substantially the entire
length of the sleeve. The sleeve has a rigid, radially outwardly
extending flange captured between the ends of the conduit portions, and a
flexible gasket between the flange and the end of one of the conduit
portions.

[0013]U.S. Pat. No. 5,425,232, which issued to Holtermann on Jun. 20,
1995, describes a marine propulsion device with means for supplying
secondary air to a catalytic converter. The marine propulsion device
comprises a combustion chamber, an exhaust passage, an air pump and a
three-way catalytic converter. The air pump pumps air into the exhaust
passage at or immediately upstream of the catalytic converter. By this
construction the internal combustion engine can be run slightly rich, but
the catalytic converter will see a close to stoichiometric mixture so
that the pollutants in the exhaust stream can be oxidized or reduced
appropriately since the catalytic converter will be able to operate as a
three-way catalytic converter.

[0014]U.S. Pat. No. 5,433,634, which issued to Nakayama et al. on Jul. 18,
1995, describes an exhaust treatment for an outboard motor. The exhaust
gases are normally discharged to the atmosphere at a point below the
level of the body of water in which the watercraft is operating. A
catalyst bed is provided in the exhaust system and the catalyst bed is
protected from damage by pumping water from the exhaust conduit in
response to certain conditions. These conditions may be either rapid
deceleration of the engine or watercraft, stopping of the engine, or any
of the combination of sensed factors. The water is pumped by a water pump
which is positioned either in the outboard drive or in the hull of an
associated watercraft. The pumping of water is initiated for only a
predetermined time and until the sensed condition no longer is existent.

[0015]U.S. Pat. No. 6,053,785, which issued to Kato et al. on Apr. 25,
2000, describes an exhaust system and control for a marine propulsion
engine. An outboard motor exhaust system and control for insuring good
running and effective exhaust gas silencing and treatment is provided.
The system includes a very compact exhaust system that includes an
expansion chamber formed beneath the exhaust guide plate and to which the
exhaust gases are delivered and removed at optimal locations.
Furthermore, a feedback control employing a combustion condition sensor
is employed along with a catalyst in the exhaust. Sensors are provided
upstream and downstream of the catalyst to insure that it is operating at
optimum conditions.

[0016]U.S. Pat. No. 6,116,022, which issued to Woodward on Sep. 12, 2000,
describes a catalytic reactor for marine applications. The reactor for an
internal combustion engine has a cooling jacket surrounding multiple
catalyst elements. A thermal barrier layer is formed between the catalyst
elements and the cooling jacket to prevent overcooling of the catalyst
elements. The thermal barrier layer can be formed from insulating
elements such as fibrous material, a plurality of annular rings disposed
around the catalyst elements, a corrugated layer, or can be formed by an
empty space.

[0017]U.S. Pat. No. 6,368,726, which issued to Holpp et al. on Apr. 9,
2002, describes a honeycomb body configuration. It includes a honeycomb
body with a fluid inlet side and a fluid outlet side. The honeycomb body
is formed of at least partially structured sheet metal layers which form
channels through which a fluid can flow. The honeycomb body is surrounded
by an inner tubular jacket and an outer tubular jacket provided
concentrically in relation thereto. The inner tubular jacket is
configured as a corrugated hose in at least one axial subregion thereof.
The inner tubular jacket has at least one further axis subregion which
lies smoothly against the honeycomb body. The corrugated subregion and
the outer tubular jacket are connected at least in a longitudinal partial
region of the corrugated subregion.

[0018]U.S. Pat. No. 6,639,193, which issued to Schaper on Oct. 28, 2003,
describes a method and apparatus for end-surface connection of a carrier
matrix of a honeycomb body by a joining technique. It relates in
particular to a catalyst carrier body. The matrix is disposed in a
tubular jacket and is laminated and/or wound from at least partially
structured sheet metal foils or layers. The end surface of the honeycomb
body is at least partially heated with the aid of a surface inductor
having induction coils.

[0019]U.S. Pat. No. 6,660,235, which issued to Holpp et al. on Dec. 9,
2003, describes a catalyst carrier configuration for installation close
to an engine. It includes a housing and at least one catalyst carrier
body disposed in the housing. The catalyst carrier body has partition
walls defining a plurality of passages for an exhaust gas. A flange
surrounds the catalyst carrier body and extends radially outwards from
the catalyst carrier body. The flange has a second that extends at least
partially into an outer wall of the housing and can be disposed between a
cylinder head and a manifold of an internal combustion engine. The
catalyst carrier configuration can be mounted close to an internal
combustion engine. A structural unit having at least two catalyst carrier
configurations and an exhaust system are also provided.

[0020]U.S. Pat. No. 6,740,178, which issued to Kurth et al. on May 25,
2004, describes a method for producing a centered honeycomb body. The
method includes forming a honeycomb body by stacking and/or winding
layers of steel sheet containing chromium and aluminum resulting in the
honeycomb body having channels through which a fluid can flow. The
honeycomb body is introduced into a tubular jacket.

[0021]U.S. Pat. No. 6,799,422, which issued to Westerbeke et al. on Oct.
5, 2004, describes an emission control method. It is intended for use
with a fixed speed internal combustion engine and includes injecting a
controlled flow of air into the exhaust between a first catalyst bed
adapted to reduce hydrocarbon and nitrogen oxide emissions and a second
catalyst bed adapted to reduce carbon monoxide emissions.

[0022]The patents described above are hereby expressly incorporated by
reference in the description of the present invention.

SUMMARY OF THE INVENTION

[0023]An exhaust system for a marine engine made in accordance with a
preferred embodiment of the present invention comprises a first catalyst
device comprising a first catalyst material disposed within a first
housing structure. The first housing structure has a first generally
tubular portion which, in turn, has a first axis. A first rim portion
extends from an end of the first generally tubular portion and is
disposed in a plane which is generally perpendicular to the first central
axis.

[0024]A first housing structure is configured to direct exhaust gas away
from the marine engine and is provided with a first flange surface. A
second housing structure is configured to direct exhaust gas away from
the first housing structure and has a second flange surface. A gasket is
provided and the first and second housing structures are configured to be
attached together with the gasket being disposed between the first and
second flange surfaces. The gasket has a first opening formed through its
thickness and the first opening is configured to receive the rim portion
therein. The rim portion is not compressed between the gasket and either
the first or second flange surface.

BRIEF DESCRIPTION OF THE DRAWINGS

[0025]The present invention will be more fully and completely understood
from a reading of the description of the preferred embodiment in
conjunction with the drawings, in which:

[0026]FIG. 1 is a side view of a marine engine which is partially
sectioned to show internal portions of the exhaust system;

[0027]FIG. 2 is an isometric partially sectioned view of the port and
starboard exhaust components;

[0028]FIG. 3 is a section view of the port exhaust system of a marine
engine;

[0029]FIG. 4 is a partially sectioned isometric view of the device shown
in FIG. 3;

[0030]FIG. 5 is an exploded isometric view of the port side exhaust system
of the present invention;

[0031]FIG. 6 is a section view of the port side exhaust system of a marine
engine; and

[0032]FIG. 7 is an alternative exhaust system using an oblong catalyst
device.

DESCRIPTION OF THE PREFERRED EMBODIMENT

[0033]Throughout the description of the preferred embodiment of the
present invention, like components will be identified by like reference
numerals. In the following description of various embodiments of the
present invention, certain configurations will be described and
illustrated as having three catalyst devices used together as a system.
It should be clearly understood that the catalyst devices can
alternatively be combined together in systems comprising less than or
greater than this number. In addition, it should also be clearly
understood that certain embodiments of the present invention can comprise
a single catalyst device. All of these alternative configurations are
described below in relation to an exemplary engine arrangement. In
addition, it should be understood that a catalyst system made in
accordance with a preferred embodiment of the present invention, when
used in conjunction with a V-type engine, would typically be provided at
both sides, or cylinder banks, of the engine.

[0034]FIG. 1 shows a marine engine 10 within the structure of a marine
vessel 12. Although not shown in FIG. 1, the crankshaft of the engine 10
is supported for rotation about a horizontal axis and attached in torque
transmitting relation with a driveshaft that extends through the transom
14 to provide motive power to a marine propulsion drive (not shown in
FIG. 1). The marine engine 10 has a plurality of exhaust ports 20
configured to conduct exhaust gas from a plurality of cylinders within
the structure of the engine. A first exhaust conduit 22 is disposed in
fluid communication with the plurality of exhaust ports 20. The first
exhaust conduit 22 performs the function of an exhaust manifold which
receives the exhaust gas from the plurality of exhaust ports 20 and
directs it away from the engine 10. A plurality of catalyst devices 23-25
is disposed in fluid communication with the first exhaust conduit 22. The
plurality of exhaust conduits, as will be described in greater detail
below, are configured and arranged in cooperation with the first exhaust
conduit 22 to assure that all of the exhaust gas passes through the
plurality of catalyst devices 23-25. A second exhaust conduit 28 is
disposed in fluid communication with the plurality of catalyst devices
23-25. The catalyst devices are disposed in serial fluid communication
between the first and second exhaust conduits, 22 and 28. Each one of the
plurality of catalyst devices 23-25 is disposed in parallel fluid
communication with each other.

[0035]With continued reference to FIG. 1, the first exhaust conduit 22, or
exhaust manifold, is disposed in serial fluid communication between the
plurality of exhaust ports 20 and the plurality of catalyst devices
23-25. The second exhaust conduit 28 is disposed in serial fluid
communication with the plurality of catalyst devices 23-25. The catalyst
devices 23-25 are aligned along a common plane. The common plane is
generally vertical and extends in a direction which is generally parallel
with a crankshaft of the engine 10.

[0036]Each of the catalyst devices 23-25, in a particularly preferred
embodiment of the present invention, comprises a cylindrical housing. The
housing can alternatively be generally tubular and non-cylindrical. A
catalyst material is disposed within the generally tubular housing
structure of each of the catalyst devices 23-25. A central housing 30, or
catalyst housing structure, is provided to retain the catalyst devices
23-25 in their proper positions relative to both the first and second
exhaust conduits, 22 and 28. The path of the exhaust gas E is represented
by the arrows in FIG. 1. The exhaust gas travels from the plurality of
exhaust ports 20, through the first exhaust conduit 22, through the
catalyst devices 23-25, and through the second exhaust conduit 28. From
there, as is generally understood by those skilled in the art, the
exhaust gas is directed away from the engine 10 either through the
transom 14 and to an underwater outlet or through exhaust pipes above and
to the rear of the engine 10.

[0037]With continued reference to FIG. 1, it should be understood that one
of the advantages of a preferred embodiment of the present invention is
that the use of three catalyst devices 23-25 reduces the overall required
size of the components associated with the exhaust system. In other
words, three catalyst devices 23-25 of a lesser diameter can be aligned
as shown in FIG. 1 in a space that requires less overall width of the
engine structure than would be needed if a single circular catalyst
device was used. It should be understood that, when the marine engine 10
is a V-type engine, two exhaust systems are provided, one on the port
side of the engine as shown in FIG. 1 and a similarly configured exhaust
system on the starboard side of the engine.

[0038]FIG. 2 is an isometric and partially sectioned view of two exhaust
structures used in conjunction with one embodiment of the present
invention. A port exhaust structure 40 and a starboard exhaust structure
42 are shown in FIG. 2. The port exhaust structure 40 is sectioned to
illustrate various internal characteristics. The exhaust manifold, or
first exhaust conduit 22, directs the exhaust gas E from exhaust ports of
the engine, as described above, through a plenum region 44. The central
housing structure 30, or catalyst housing structure, has a plurality of
generally tubular cavities 43-45 formed therein. Each of the tubular
cavities is shaped to receive one of the catalyst devices 23-25 which are
described above in conjunction with FIG. 1. Those catalyst devices are
not shown in FIG. 2. Each of the tubular cavities 43-45 is sized to
define a space between an inner surface, such as surfaces 47-49, of the
cavities 43-45, respectively, and an outer surface of the generally
tubular structure of the catalyst devices 23-25. This generally annular
space thus defined by the sizes of the catalyst devices 23-25 and the
generally tubular cavities 43-45 provides an important thermally
insulative function between the catalyst devices and the catalyst housing
structure 30. As shown in FIG. 2, cooling passages 50 are provided to
limit the temperature of the first exhaust conduit 22, the catalyst
housing structure 30, and the second exhaust conduit 28. However, many
types of catalyst devices operate more efficiently and effectively at
raised temperatures. Therefore, it can become counterproductive if the
catalyst devices 23-25 receive a cooling effect as a result of the water
passing through the cooling passages 50. By providing a space between the
catalyst devices 23-25 and there respective tubular cavities 43-45, this
cooling effect is reduced. As a result of this insulating space, the
catalyst devices 23-25 operate at higher temperatures because of the
temperature of the exhaust gas E passing through them.

[0039]FIG. 3 is a sectioned view of the port exhaust device 40. With
particular reference to catalyst device 23 in FIG. 3, it can be seen that
the outer surface 54 of the generally tubular member 56 is smaller than
the inner surface 60 of the associated tubular cavity which is described
above in conjunction with FIG. 2 and identified by reference numeral 43.
This difference in size between the outer surface 54 and the inner
surface 60 defines the generally annular space 70 surrounding the
catalyst device 23. As a result, heat is not efficiently communicated
away from the catalyst device 23 toward the inner surface 60 of the
tubular cavity which is cooled by the water passages 50. The catalyst
devices 23-25 therefore operate at higher temperatures than would be
possible if their tubular structures were in direct thermal contact with
the inner walls of their associated tubular cavities.

[0040]FIG. 4 is a partially sectioned view of the port exhaust device 40.
The view of FIG. 4 is a section taken along a plane that is generally
horizontal and intersects the catalyst housing structure 30 and the three
catalyst devices 23-25. This plane of intersection is illustrated in FIG.
3 and identified by dashed line 66.

[0041]In FIG. 4, the space between the outer surface 54 of the tubular
catalyst device and the inner cylindrical surface 60 of the tubular
cavity is identified by reference numeral 70. This space is generally
annular and circular in cross-section except in the region directly
between adjacent catalyst devices 23-25. In that region the space,
identified by reference numeral 72, is larger because of the geometry of
the components and the fact that adjacent tubular cavities, identified by
reference numerals 43-45 in FIG. 2, are not isolated from each other.
Also shown in FIG. 4 is a water jacket 50 surrounding the wall 76 that
defines the generally tubular cavities 43-45.

[0042]FIG. 5 is an isometric view of the port exhaust device 40 with the
catalyst housing structure 30 separated to expose the three catalyst
devices 23-25. The exploded view of FIG. 5 also shows the catalyst
devices 23-25 spaced apart from the first exhaust conduit 22 or exhaust
manifold. Several characteristics of the preferred embodiment of the
present invention can be seen in the exploded isometric view of FIG. 5.
Each of the catalyst devices 23-25 has a tubular portion, which is
generally cylindrical in the embodiment shown in FIG. 5, and a rim 80
which is configured to lie in a plane which is generally perpendicular to
a central axis of the tubular portion of the catalyst device. These rims
80 are configured to support the associated catalyst device on an upper
surface 84 of the first exhaust conduit 22, or exhaust manifold. In other
words, the outer diameter of the rim 80 is greater than the inner
diameter 86 of an associated opening formed in the upper surface 84 of
the exhaust manifold or first exhaust conduit 22. These relative sizes of
the openings 86 and rims 80 prevent the catalyst devices 23-25 from
passing into the associated opening 86. When the catalyst housing
structure 30 is attached to the exhaust manifold 22, the rims 80 of the
catalyst devices 23-25 are captured between opposed flange surfaces.
Under the rims 80 is the surface identified reference numeral 84 and
above the rims 80 is the lower surface of the catalyst housing structure
30. As a result of the space 70 described above in conjunction with FIG.
4, the catalyst devices 23-25 are generally in non-contact association
with the catalyst housing structure 30. They are supported by their
relationship of the rims 80 with the upper surface 84 of the first
exhaust conduit 22 and a lower surface of the catalyst housing structure
30.

[0043]With continued reference to FIG. 5, a gasket 90 is disposed on the
flange surface 84 of the first exhaust conduit 22. It has a central
opening 92 formed therethrough. The central opening 92 formed through the
gasket 90 is sized to allow the rims 80 to rest on the surface 84 within
the size of the opening 92. In other words, when the catalyst housing
structure 30 is attached to the exhaust manifold 22, the rims 80 are in
contact with surface 84 and the lower surface of the catalyst housing
structure 30, but the gasket 90 is not disposed between the rims 80 and
either surface.

[0044]With reference to FIGS. 3 and 5, it can be seen that the rims 80
provide a seal at the bottom of the spaces identified by reference
numerals 70 and 72 and described above in conjunction with FIG. 4. This
seal at the bottom of these spaces inhibits a liquid, such as water, from
flowing downward out of the spaces 70 and 72. As such, the seal
cooperates with the space to form a reservoir that captures water which
may flow along the walls of the catalyst housing structure 30 under the
effect of gravity. This water can result from condensation formed on the
inner walls of the catalyst housing structure 30. If that condensation
occurs, the seal provided by the rims 80 at the bottom portions of the
catalyst devices 23-25 inhibits the flow of that water into the exhaust
manifold 22 and, eventually, into the exhaust ports of the engine. When
the catalyst devices 23-25 reach elevated temperatures, as a result of
their direct exposure to the exhaust gas E, the increased temperature
will boil the captured water within the reservoir of the spaces 70 and 72
and that resulting water vapor will pass upwardly through the catalyst
housing structure 30 and out of the second exhaust conduit 28 with the
exhaust gas.

[0045]FIG. 6 is a section view of the exhaust manifold 22, or first
exhaust conduit, and the catalyst housing structure 30 attached to it.
FIG. 6 also shows the surface 100 of the exhaust manifold which can be
rigidly attached to a surface of the engine through which exhaust gas is
conducted through its exhaust ports. Reference numeral 102 identifies a
gasket between surface 100 of the exhaust manifold 22 and the
corresponding surface of the engine surrounding the exhaust ports. The
exhaust gas E flows from the exhaust ports of the engine, through the
exhaust manifold 22 and through the catalyst devices 23-25 as described
above in conjunction with FIGS. 1-5. The space 70 is shown in FIG. 6
surrounding the outer surface 54 of the generally tubular portion of the
catalyst device and the inner surface 60 of the generally tubular cavity
formed within the catalyst housing structure 30.

[0046]Throughout the description of the exhaust system with reference to
FIGS. 1-6, the catalyst devices 23-25 have been illustrated and described
as being s generally cylindrical in cross-section. However, it should be
understood that this generally cylindrical shape is not necessary in all
embodiments of the present invention. As an example, an oblong-shaped
catalyst device can also be used. FIG. 7 shows an oblong-shaped catalyst
device 123 disposed within a catalyst housing structure 130. The oblong
nature of the catalyst device can be seen from its major axis 132 and the
arrow 134 which represents half of its minor axis illustrated in the
section view of the catalyst device 123 in FIG. 7. The structure shown in
FIG. 7 directs exhaust gas through four pipes 141-144 which conduct the
exhaust gas to a plenum region 144 where the exhaust gas from each pipe
is free to combine with gas from other pipes within the plenum 144 of the
catalyst housing structure 130. The exhaust gas passes through the plenum
144 and then through the catalyst device 123. After flowing through the
catalyst device 123, the exhaust gas E flows into and through the second
exhaust conduit 28.

[0047]The exhaust system described above in conjunction with FIGS. 1-7
exhibits numerous advantageous characteristics which improve the
operation of a marine engine. These characteristics will be described in
greater detail below in conjunction with the specific figures that best
illustrate those characteristics.

[0048]FIG. 7 illustrates the oblong catalyst device 123 and FIG. 1 shows
the relative positions of the exhaust ports 20 on the marine engine 10.
It should be understood that the generally cylindrical exhaust devices
23-25 could be replaced within the catalyst housing structure 30 by an
appropriately shaped oblong catalyst device such as that which is
identified by reference numeral 123 in FIG. 7.

[0049]With reference to FIGS. 1 and 7, one embodiment of the present
invention comprises a plurality of exhaust ports 20, a first exhaust
conduit, 22 or 122, an oblong catalyst device 123 and a second exhaust
conduit, 28 or 128. The first exhaust conduit 122 is disposed in fluid
communication with the plurality of exhaust ports by the exhaust pipes
141-144. The oblong catalyst device 123 is disposed in fluid
communication with the first exhaust conduit, 22 or 122. The oblong
catalyst 123 has a major axis 132, a minor axis, half of which is
represented by arrow 134, and a central axis which extends through the
catalyst device in a direction generally parallel to the arrows
representing the flow of exhaust gas E. The oblong catalyst device is
configured to conduct the exhaust gas E in a direction generally
perpendicular to the major and minor axes, 132 and 134, and generally
parallel to the central axis. The second exhaust conduit, 28 or 128, is
disposed in fluid communication with the oblong catalyst device 123. The
oblong catalyst device is disposed in serial fluid communication between
the first and second exhaust conduits, 122 and 128.

[0050]The configuration of a preferred embodiment of the present
invention, described above in conjunction with FIGS. 1-7, promotes a
generally uniform flow of exhaust gas through the catalyst module,
whether the catalyst module comprises a plurality of catalyst devices
23-25 or whether it comprises a single larger catalyst device 123. With
reference to FIGS. 2 and 6, the exhaust gas E flowing into the exhaust
manifold 22, or first exhaust conduit, flows from regions of relatively
smaller cross-sectional area (e.g. the exhaust ports of the engine) to a
plenum area 44 having a greater cross-sectional area. As a result of this
increase in cross-sectional area along the path of the exhaust gas E, the
velocity of the exhaust gas decreases. This allows the exhaust to more
uniformly seek areas of lower pressure along the inlet surfaces of the
catalyst devices 23-25. In other words, without the plenum area 44, the
exhaust gas stream would be more subject to the influences of gas stream
velocity and momentum that could urge the exhaust to flow through limited
portions of the inlet area of the catalyst devices. However, when a
plenum 44 is provided, the velocity of the gas stream slows and allows
the exhaust to more uniformly seek lower pressure areas along the inlet
surfaces of the catalyst devices. Rather than directing the exhaust gas
stream with a restrictive conduit, the expanded area 44 of the plenum
decreases the velocity of the flow and encourages a more uniform
distribution of the exhaust gas through the plurality of exhaust devices
or, alternatively, through all of the areas of the inlet of a single
catalyst device.

[0051]With reference to FIGS. 1 and 3, a non-catalytic porous member 150
is disposed within the second exhaust conduit 128. This non-catalyst
porous member can be made of the same material used to begin the
manufacturing process associated with the catalyst devices 23-25. That
manufacturing process is described in U.S. Pat. Nos. 6,368,726 and
6,639,193. U.S. Pat. Nos. 6,660,235 and 6,740,178 also describe the
manufacturing process associated with creating a catalyst device. The
internal portions of the catalyst devices described in those patents
comprise a support structure which is porous. The support. structure is
also provided with a catalytic material to manufacture a catalyst device.
The non-catalytic porous member 150 comprises the internal support
structure, but without the catalytic material being included. Its purpose
is not to serve as a catalyst device. Its purpose is to serve as a
structure which inhibits the flow of liquid water in a reverse direction
through the second exhaust conduit 28. Exhaust gas freely passes through
the porous non-catalytic member as it flows away from the engine 10. As a
result, the non-catalytic porous member is heated to approximately the
temperature of the exhaust gas stream. If water attempts to migrate in a
reverse direction through the non-catalytic porous member 150, it will be
rapidly evaporated and the resulting vapor will be carried away from the
engine 10 by the exhaust stream. This embodiment of the present invention
provides an exhaust conduit 128 disposed in serial fluid communication
downstream from a plurality of exhaust ports 20 as described above. The
non-catalytic porous member can comprise a metallic mesh material and it
can be configured to direct the exhaust gas through the metallic mesh
material. In a preferred embodiment, the non-catalyst porous member
comprises a metallic catalytic substrate, but without a catalytic
coating.

[0052]The embodiment of the present invention described above in
conjunction with FIGS. 1-6 comprises a catalyst device (e.g. devices
23-25) that comprises a first catalyst material disposed within a first
housing structure, such as the tubular or cylindrical structure
illustrated in FIG. 5. The tubular portion of the catalyst devices has a
central axis. The rim portion 80 extends from an end of the generally
tubular portion and is disposed in a plane which is generally
perpendicular to the central axis of the tubular portion. A gasket 90 is
disposable between the exhaust manifold 22 and the catalyst housing
structure 30. The gasket 90 is disposed between the two flange surfaces
which include the upper surface 84 of the exhaust manifold 22 and the
lower surface of the catalyst housing structure 30. The gasket has an
opening 92 which is formed through its thickness. The opening 92 is
configured to receive the rim portion 80 of a catalyst device. The size
of the opening 92 is selected to allow the rim portions 80 to be captured
between the upper surface 84 of the exhaust manifold 22 and the lower
surface of the catalyst housing 30 without the gasket 90 being compressed
between the rim portion 80 and either of the two flange surfaces.

[0053]As described above in conjunction with FIGS. 3, 4 and 6, the outer
surface 54 of each tubular catalyst device 23-25 is shaped to be received
within an associated tubular cavity 43-45 with a space 70 therebetween.
The space 70 is a generally annular space defined by the difference in
size between the outer surface 54 of the catalyst devices 23-25 and the
inner surface 60 of the associated tubular cavity. This space 70 provides
an effective thermal insulation between the catalyst devices 23-25 and
the catalyst housing structure 30. The presence of the rim 80 at the
bottom portion of each catalyst device 23-25 provides a seal which
prevents liquid from flowing downward and out of the space 70 if liquid
is trapped therein. As a result, a reservoir is defined which holds the
liquid until the temperature becomes sufficiently high to boil the liquid
and allow the water vapor to escape with the gas stream.

[0054]With reference to FIG. 5, a concentricity spacer 160 is provided for
each of the catalyst devices 23-25. The purpose of the concentricity
spacer is to maintain the outer cylindrical surface of the catalyst
devices in a concentric relationship with the inner cylindrical surface
of the associated tubular cavity 43-45. The concentricity spacer 160, in
a preferred embodiment of the present invention, comprises a relatively
thin sheet of material that is embossed with raised portions which
maintain the concentricity of the catalyst device and its associated
tubular cavity while allowing fluid to flow in a vertical direction past
the concentricity spacer.

[0055]With reference to FIGS. 3 and 4, two oxygen sensors are illustrated.
An upstream oxygen sensor 170 is disposed in fluid communication with the
exhaust gas passing through the exhaust manifold 22. A downstream oxygen
sensor 175 is disposed in the upper portion of the catalyst housing
structure 30.

[0056]As shown in FIG. 4, the upstream oxygen sensor 170 is disposed
within the overall exhaust structure and, more specifically, within the
exhaust manifold 22. It is therefore disposed downstream from the
plurality of exhaust ports 20 (shown in FIG. 1) and upstream from the
catalyst devices 23-25. The oxygen sensor 170 is configured to remain at
or below the temperature of the exhaust gas E when the exhaust gas is
flowing from the plurality of exhaust ports 20 as shown in FIG. 1. In
other words, the oxygen sensor 170 located upstream from the catalyst
devices 23-25 is unheated other than the effect it experiences from the
hot exhaust gas flowing over it. The unheated nature of the upstream
oxygen sensor 170 provides a significant advantage because it is less
susceptible to damage in the event that liquid, such as water condensate,
flows in a reverse direction from the second exhaust conduit 28 toward
the plurality of exhaust ports of the engine 10. If the upstream oxygen
sensor 170 is heated, as most oxygen sensors now are, it could be
severely damaged if water flows in contact with it. The use of an
unheated oxygen sensor 170 therefore provides a significant benefit in an
exhaust system of a marine engine.

[0057]FIG. 3 illustrates an advantage provided by the system described
herein in conjunction with a reverse flow of liquid, as represented by
arrows W, from the second exhaust conduit 28 toward the catalyst devices
23-25. The downstream oxygen sensor 175 is disposed within the catalyst
housing structure 30 and in fluid communication with the plurality of
exhaust ports 20 described above in conjunction with FIG. 1. It is also
disposed in fluid communication with the second exhaust conduit 28. The
second exhaust conduit 28 is connected to a first portion of the catalyst
housing structure 30 which, as illustrated in FIG. 3, is at the upper
right portion of this device. The oxygen sensor 175 is connected to a
second portion of the catalyst housing structure 30 which is located at
the upper left portion as shown in FIG. 3. In a preferred embodiment of
the present invention, the first and second portions are disposed at
opposite sides of the catalyst housing structure 30 as shown.

[0058]With continued reference to FIG. 3, the first exhaust conduit 22,
the catalyst housing structure 30 and the catalyst device 23-25 are
configured and arranged to cooperatively define a reversion liquid
trajectory path W for water that flows in a direction from the second
exhaust conduit 28 toward the first exhaust conduit 22. This reversion
liquid trajectory path is governed by the positions of the second exhaust
conduit 28 and the catalyst devices 23-25 in conjunction with the
resulting inertia of the water droplets as they flow under the effect of
differential pressure that can result from the opening of exhaust valves
of the engine.

[0059]The causes for water reversion are well known to those skilled in
the art of marine propulsion systems. As water droplets are caused to
flow in a reverse direction, as indicated by arrows W, the trajectory of
those water droplets is governed by the magnitude of the differential
pressure between the second exhaust conduit 28 and the first exhaust
conduit 22 in conjunction with the size of the various droplets, the
shape of the internal cavity of the catalyst housing structure 30, and
the positions of the upper portions of the catalyst devices 23-25. The
location of the downstream oxygen sensor 175 is selected, in a preferred
embodiment of the present invention, to be away from this reversion
liquid trajectory path illustrated by arrows W in FIG. 3. As such, the
water droplets are less likely to strike the downstream oxygen sensor
175. This advantageous location of the downstream oxygen sensor 175
therefore avoids damage that would otherwise occur to it if the hot
sensor 175 is struck by water droplets flowing in a reverse direction
from the second exhaust conduit 28 toward the catalyst devices 23-25.

[0060]Although the present invention has been described in particular
detail and illustrated to show various embodiments, it should be
understood that alternative embodiments are also within its scope.

Patent applications by Brian R. White, Stillwater, OK US

Patent applications by Derric Drake, Stillwater, OK US

Patent applications in class Treating exhaust with a catalyst

Patent applications in all subclasses Treating exhaust with a catalyst